In recent years, in a field of a semiconductor device, there have been (i) an improvement in performance of each of various semiconductor elements and (ii) developments of a high-speed data transmission technology. This allows a dramatic improvement in operation speed of a large-scale integrated circuit (LSI). However, a problem is still unsolved that, in spite of the speed-up of internal operations of the LSI, a print substrate on which the LSI is provided has at least the following problems due to an increase in operation frequency: (i) an increase in transmission loss occurred in electric wiring; (ii) an increase in noise, and (iii) an increase in electromagnetic block. This made it significantly difficult to transmit, without any problems, a signal having an operation frequency of greater than 1 GHz on the print substrate which requires complicated wiring. Therefore, for the purpose of ensuring signal quality, it has been necessary to take a measure (i) to limit a wiring design in view of the operation frequency, (ii) to keep the operation frequency low, and/or the like. Thus, it has been impossible to fully bring out the inherent performance of the LSI.
In view of the problems of the semiconductor device, it has recently been considered and put into practical use to apply an optical interconnection technology for connecting the LSI with the use of an optical fiber. According to the optical interconnection technology, in general, (i) an electric signal is converted into an optical signal, (ii) the optical signal thus obtained is transmitted via an optical fiber, and then (iii) the optical signal thus transmitted is converted into an electric signal. The conversion of the electric signal into the optical signal and vice versa are carried out by an optical semiconductor element. Accordingly, the optical semiconductor element and the optical fiber should be connected to each other in the semiconductor device, while their positioning is being secured. For example, Patent Literatures 1 through 3 disclose various optical semiconductor modules and semiconductor devices each of which secures positioning of the optical semiconductor element and the optical fiber.
Each of Patent Literatures 1 and 2 discloses an optical module in which the optical fiber and the optical semiconductor element are integral with each other. FIG. 22 is a cross-sectional view illustrating an arrangement disclosed in Patent Literature 1 in which the optical module is connected to a semiconductor device 120. As illustrated in FIG. 22, the semiconductor device 120 disclosed in Patent Literature 1 has an arrangement in which a semiconductor element 102 and an optical module 110 are connected to each other via a wire 105, and the optical module 110 and the wire 105 are partially covered by a sealing portion 107. According to the optical module 110, an optical semiconductor element 103 is fixed, via a conductive layer 106, to a support portion 104 provided on a peripheral surface of the optical fiber 130. This arrangement secures the positioning of the optical semiconductor element 103 and the optical fiber 130, and realizes a semiconductor device that is easy to manufacture. Patent Literature 2 also discloses an optical module similar to the optical module 110 disclosed in Patent Literature 1.
Further, Patent Literature 3 discloses an optical semiconductor module in which an optical fiber and an optical semiconductor element are provided separable from each other. FIG. 23(a) is a cross-sectional view illustrating an arrangement of an optical semiconductor module 210 disclosed in Patent Literature 3, and FIG. 23(b) is a cross-sectional view illustrating an arrangement of a semiconductor device 260 including the optical semiconductor module 210. As illustrated in FIG. 23(a), the optical semiconductor module 210 disclosed in Patent Literature 3 includes a guide 212. The guide 212 has: a positioning through-hole 211 for an optical transmission path; an optical semiconductor receiving surface 212a that is one end surface of the optical transmission path located in the positioning through-hole 211, which one end surface is exposed in the positioning through-hole 211; and a wiring layer 208 provided on the optical semiconductor receiving surface 212a. Further, the optical semiconductor receiving surface 212a of the guide 212 is provided with an optical semiconductor element 203 so that a light emitting surface or a light receiving surface of the optical semiconductor element 203 faces the one end surface of the optical transmission path. This causes the optical semiconductor element 203 to be electrically connected to the wiring layer 208. Furthermore, a driving semiconductor element 213 for driving the optical semiconductor element 203 is provided adjacent to the optical semiconductor element 203 so as to be provided inside the optical semiconductor module 210. According to the optical semiconductor module 210, the optical fiber is inserted in the positioning through-hole 211, so as to (i) secure the positioning of the optical semiconductor element 203 and an optical fiber 250, (ii) reduce the size of the optical semiconductor module 210, and (iii) reduce cost.
Further, as illustrated in FIG. 23(b), the semiconductor device 260 includes a signal processing LSI 202 which is connected via bumps, by flip chip bonding, onto a substrate 201 having high-speed signal wiring. Moreover, the substrate 201 provided with the signal processing LSI 202 is further provided with two optical semiconductor modules 210. According to the semiconductor device 260, it is possible to (i) secure the positioning of the optical semiconductor element 203 and the optical fiber 250 and (ii) realize, at low cost, such a wiring structure in which optical wiring is applied to LSI wiring.
Citation List
Patent Literature 1
Japanese Patent Application Publication, Tokukai, No. 2000-347072 A (Publication Date: Dec. 15, 2000)
Patent Literature 2
Japanese Patent Application Publication, Tokukai, No. 2006-054259 A (Publication Date: Feb. 23, 2006)
Patent Literature 3
Japanese Patent Application Publication, No. 2006-053266 (Feb. 23, 2006)